What I'd really like to see is parallel constructions.  When we are talking about ruling planets with billions of population, collectively a whole planet can only build one thing at a time.

A few months prior to WoM launch, I seem to recall Brad mentioning he was pondering making a small patch for GC2 ... but that kinda vanished I guess due to Brad having to rip his frog-hair out and fix WoM.  It would be nice if GC2 gets some attention, but I doubt its going to get any significant new features like a revamped production system.

I think someone would have to dig into the .EXE.  I've only seen a few games, like The Elder Scrolls IV:  Oblivion and Star Trek:  Armada II where sufficiently hard-core programmers dig in that deeply to mod a game.